1985 Magazine Article Jim Buckley Rumford Fireplaces

[ctyankee]

From Old House Journal 1985, all you wanted to know and more on Rumford retrofit, revival fireplaces.

 

[ctyankee]

Two, I thought, interesting points.

Rumford on fireplaces (radiant heat): "One must never forget that it is the room that heats the air, and not the air which heats the room.

Buckley: "People often want to compare fireplaces with stoves. Stoves are basically air heaters, so you rely on convection to help heat adjoining rooms, or you can use fans to circulate the warm air much like a warm air furnace does. Fireplaces, however, heat only what they 'see'; you can't pump 60-degree warm air to help heat a 60-degree cool adjoining room. On the other hand, you can't lose radiant heat through infiltration or convection. "

 

[bholler]

Stoves are basically air heaters, so you rely on convection to help heat adjoining rooms, or you can use fans to circulate the warm air much like a warm air furnace does. Fireplaces, however, heat only what they 'see'; you can't pump 60-degree warm air to help heat a 60-degree cool adjoining room. On the other hand, you can't lose radiant heat through infiltration or convection. "

There are plenty of stoves that are just radiant heaters. And once the radiant heat hits objects it can then convert to convective heat.

 

[stoveliker]

I think the division between radiative and convective heating is not that useful.

We are talking about heating. Not an ambiance fire or a quick chill chase. This means it's a persistent thing.

At that point a stove heats the air by convection and also heats radiatively. ( I can't sit in front of my stove when it's going well for more than 2 minutes before my skin gets burned.) The (convective) air also heats the surrounding solid objects. Maybe a bit slower than the radiative heating, but for heating we are not talking about speed; not a chill chaser but a persistent heating. (The rest is not heating but ambiance. Perfectly fine, but a different beast.)

A radiative fireplace heats the air a little (the CO2 does absorb a bit of infrared), and heats IR absorbing materials (most solid objects) much more. Those will heat the air as well in second order.

So over the course of time, it is only the total heat output into the home that matters. Not whether it is convective or radiant. This is because things equilibrate in temperature.

The difference is only in experience; sitting in front of a radiant appliance gets your front comfortable quicker, but your back (or the backside of the couch or chair) remains colder for longer.

This, I disagree about the statement of Rumford above. He is limiting the time in which he is considering the issue. And that then is not heating anymore but ambiance.

And you can't lose radiant heat through leakage is not true either. It heats your front, but if a waft of cold air leaks in, it'll make you cold and it makes the objects in the room cold. (And hence fireplaces are poor heaters, even if good ambiance creators, because so much air needs to leak in to replenish what has been sent up the flue.)

 

[ctyankee]

Thanks for your thoughts. The context is important for both comments. Drafty houses. Put your best stove(s) in a drafty house and you'll be disappointed. (Rumford) fireplaces in the same environment will perform the task at hand possibly just as well. Using a lot more wood of course. Stoves are very limited in their btu output. A fireplace can create a lot more btu's with lots of wood. Not Heatilators etc. I'm not talking about toy fireplaces. Real fireplaces. Stoves are better given today's houses and needs. But the idea that fireplaces did not do a good job in their context is wrong. The image of colonials huddling around a fireplace every day near death is false. Buckley had I think 5 Rumford fireplaces going in his Victorian house in this article. He claims to have been fairly comfortable. I doubt he was lying. Anyway, I think a fuller picture is informative, interesting. Most on here don't. which is odd given it's Stove and Fireplace forum.

 

[ctyankee]

Does a staff member have and operate a real fireplace during a typical heating season? If so, I've never come across this fact on this site. I'd love to know. Not talking about have used, or repair work. Imagine if the staff didn't have wood stoves or whatever they offer help and advice on. Not as credible, right??

 

[SpaceBus]

I would love to have a Rumford fireplace, but just for the aesthetic and ambiance. They are certainly an improvement over the old massive cooking hearths, but not by much.

 

[bholler]

Thanks for your thoughts. The context is important for both comments. Drafty houses. Put your best stove(s) in a drafty house and you'll be disappointed. (Rumford) fireplaces in the same environment will perform the task at hand possibly just as well. Using a lot more wood of course. Stoves are very limited in their btu output. A fireplace can create a lot more btu's with lots of wood. Not Heatilators etc. I'm not talking about toy fireplaces. Real fireplaces. Stoves are better given today's houses and needs. But the idea that fireplaces did not do a good job in their context is wrong. The image of colonials huddling around a fireplace every day near death is false. Buckley had I think 5 Rumford fireplaces going in his Victorian house in this article. He claims to have been fairly comfortable. I doubt he was lying. Anyway, I think a fuller picture is informative, interesting. Most on here don't. which is odd given it's Stove and Fireplace forum.

Of course houses could be heated with fireplaces no one is debating that. It was done for a long time. But they can be heated with a stove or stoves much easier and with much less wood than it took with fireplaces. That same Victorian home that took 5 fireplaces to heat could be heated with 2 maybe 3 stoves.